Annual ERRCS Maintenance Items

Matt Lunny

Written by 20 August 2021

Annual ERRCS Maintenance Items


As a Public Safety OEM, Comba is often asked: “What actions should be performed for an annual inspection, or PMI (Preventive Maintenance Inspection)?” The answer is: “It depends on the local AHJ and their codes”.

Every jurisdiction will have a different set of requirements, so the following document is simply a guideline as to what Comba recommends.  

As the System Integrator, you will be required to take all recommendations and shape  them to fit the jurisdiction.

First and foremost, NFPA 1221, 2019 edition, Section 9.6.4 states that systems that are used to comply with the requirements of Section 9.6 shall be tested in accordance with 11.3.9 and – we will review those sections in a moment.  Section 9.6.14 states that all technical information documents, including frequencies, location of the donor tower, propagation delay, system components, and other supporting technical documents, are to be kept in a secure place accessible to maintenance personnel, but not to the public.  The first step of any annual inspection is to locate and review these documents. Many of Comba’s integration partners build a special, lockable box to hold these documents that is mounted on the wall adjacent to the BDA/BBU.

Section 11.3.9 states that a system test shall be conducted, documented, and signed by a person approved by the AHJ upon system acceptance and once every 12 months.  An annual inspection is mandated by code – if you have installed an ERRC System, it must be inspected annually!

To not risk any copyright infringements, I am going to recommend reading  To quickly summarize - Initial Acceptance Test Requirements state that all new systems must be verified that it meets the performance requirements of Section 9.6.  Further the section states that the testing personnel must be approved by the AHJ and all documentation of the initial testing include datasheets, drawings, DAQ, frequencies and secondary power calculations.  As stated previously, refer the NFPA for official codes and standards in

To summarize, the initial acceptance documentation shall include ALL documents to be left onsite, as stated above.  For systems connected to the fire alarm panel and NOT monitored off site, as defined by NFPA 72, the alarms shall be inspected weekly.  For systems that are monitored off site, as defined by NFPA 72, the alarms shall be inspected semiannually.

Each year, the system shall be tested to verify normal operation, and every 5 years, DAQ and RF coverage shall be tested to validate the system still passes and there has not been any deviation of coverage of more than 5% from the initial installation.  You must validate that are no changes in system frequencies.  Visual inspections and testing reports shall be documented and retained for the life of the system

If you are looking to comply with the exact letter of the law, please don’t use this document – reference the code enforced in your jurisdiction!

Below are Comba recommendations for installed equipment.  As stated at the beginning of the document, this is not an all-inclusive list, and you may need to add or modify steps to meet local jurisdiction codes, but this should provide give a general idea of steps to take:

1.       Verify on-site documentation – including design, as-builts, spec sheets, etc. – if these are not available, try to locate them and leave them onsite for future inspections.

2.       Visually check the system – ensure all components are properly secured, installed in the locations as shown on the plans, and no obvious damage or movements of equipment have occurred.

3.       BBU Inspection

a.       Verify all alarming as required by code.  You can use the “Comba Alarm Triggering” Guide if you are unsure how to do this. Check that alarming shows up on the BBU, Annunciator Panel, and FACP.  Note: you may need to put the FACP into test mode so the building owner is not notified of alarms that are occurring!

b.       Upgrade the BBU – Comba recommends to always upgrade your BBU to the latest firmware version.

c.       Re-verify the alarming (make sure everything remains the same after the upgrade).

d.       Check the battery capacity remaining – you can use a Pulse Load tester to ensure the battery life remaining is adequate.

                                                               i.      Replace batteries if needed – lead acid batteries should be replaced every 2-4 years and lithium iron phosphate batteries should be replaced every 7-10 years.

4.       BDA Inspection

a.       Isolation check – measure both UL and DL isolation manually.

b.       Input signal verification – verify the off-air signal is the same as what was recorded in the close-out documentation.  If this is not included, ensure that there is adequate input signal to cover the building.

c.       Gain check – verify both the downlink gain and uplink gain are the same as what was recorded in the close-out documentation. This should be at least 20dB less than the isolation measurement.

d.       Log into the BDA and ensure all frequencies are properly programmed and supported.

e.       Note: Upgrading the BDA firmware is not recommended for functioning systems.  If coverage issues are occurring, contact Comba technical support before upgrading.

5.       Building Inspection

a.       Complete a grid test of the building, utilizing the same grid pattern as previous tests. Complete both a DL signal strength and DAQ test – if your jurisdiction has the capability, measure the UL signal strength or perform calculations to estimate the UL signal strength at the tower.

b.       Check that all critical areas pass testing.  Record these with the grid test.

c.       Ensure that all antennas are still transmitting.  Walk underneath each antenna and measure signal strength.  This should approximately match the signal strength indicated on the heat maps as provided with the design.


After completion, it is recommended to print out all test reports and leave a dated copy with the existing onsite documentation.  This report, along with existing reports, are used to validate annual system functionality.

As previously stated, this is a recommended inspection document – please follow local requirements for test procedures and going above minimum requirements is alw